Automated vehicle inspection system

ABSTRACT

The invention integrates a general purpose computer with a controller area network to effect an inspection regimen through the controller area network A convenient user interface, combining handheld instruments and convention displays and printers allows the driver to interact with the system. The computer provides storage for programs and processing power to implement test regimens in logical order relating to completion of the inspection.

This is a division of application Ser. No. 09/920,494, filed Aug. 1,2001.

FIELD OF THE INVENTION

The present invention relates generally to commercial motor vehicles andmore particularly to an automated vehicle inspection system providingthe collection of selected data and prompting manual inspection andentry of other data to promote the generation of electronic inspectionreports in an efficient and complete manner.

DESCRIPTION OF THE PROBLEM

Commercial transport regulations provide for periodic inspection of,generation of inspection reports relating to, and documentation ofmaintenance on, commercial vehicles. Inspections include checkingnumerous operational aspects of the vehicle for conformity to normativeoperational standards, implementing a check off system for maintenancewhen indicated by inspection, as well as for scheduled maintenance, andvalidating the reports generated and keeping copies of the reports for aminimum time period.

Vehicle interactive on board computers (OBC) have been suggested in theart for use in implementing inspection programs directed to meetingregulations. The OBC suggested in U.S. Pat. No. 5,680,328 was preferablya personal or lap top computer, which is used for receiving data inputsfrom a driver or maintenance personnel as part of an inspection, and forproviding for the collection of data from various sensors placed on thevehicle. However, the '328 patent did not describe a mechanism foractually collecting data from vehicle sensors. The OBC mayelectronically store inspection reports, and provide copies of the sameon a display or in hard copy form.

Contemporary designs for the control and management of vehiclecomponents increasingly rely on methods derived from computernetworking. Digital data is exchanged between component controllers overa common physical layer such as a twisted shielded pair of wires.Intelligible communication between two or more device controllers amonga greater plurality of devices, all occurring over the common physicallayer, depends upon the communicating devices being able to discriminateamong messages they receive and to respond to particular messages. Suchmethods are well known in the art and are part of the standards whichthe Society of Automotive Engineers (SAE) has published and continues topublish as part of the SAE J1939 protocol.

The J1939 protocol provides an open protocol and a definition of theperformance requirements of the medium of the physical layer, but alsoallows for development of proprietary protocols. The SAE J1939 protocolis a specialized application of a controlled area network (CAN) and maybe readily implemented utilizing commercial integrated circuits such asthe C167 Integrated Circuit from Siemens of Germany.

The CAN protocol is an ISO standard (ISO 11898) for serial datacommunication, particularly aimed at automotive applications. The CANstandard includes a physical layer (including the data bus) and adata-link layer, which define useful message types, arbitration rulesfor bus access and methods for fault detection and fault confinement.The physical layer uses differential transmission on a twisted pair wirebus. A non-destructive bitwise arbitration is used to control access tothe bus. Messages are small, at most eight bytes, and are protected bychecksum error detection. There is no explicit address in the messages,instead, each message carries a numeric value which controls itspriority on the bus, and may also serve as an identification of thecontents of the message. CAN offers an error handling scheme thatresults in retransmitted messages when they are not properly received.CAN also provides means for removing faulty nodes from the bus. CANfurther adds the capability of supporting what are termed “higher layerprotocols” for standardizing startup procedures including bit ratesetting, distributing addresses among participating nodes or kinds ofmessages, determining the layout of the messages and routines for errorhandling on the system level.

Digital data communications over serial data paths are an effectivetechnique for reducing the number of dedicated communication pathsbetween the numerous switches, sensors, devices and gauges installed onthe vehicles. Multiplexing the signals to and from local controllers andswitches promises greater physical simplicity through displacing much ofthe vehicle wiring harness, reducing manufacturing costs, facilitatingvehicle electrical load management, and enhancing system reliability.

It would be desirable to add intelligence to a vehicle controller areanetwork conforming to the SAE J1939 standard to implement inspectionregimens.

SUMMARY OF THE INVENTION

The invention integrates a general purpose computer with a controllerarea network to effect an inspection regimen through the controller areanetwork. A convenient user interface is based on a combination of one ormore devices, including handheld instruments, conventional displays,keypads, pucks and printers, and allows the driver to interact with thesystem. The computer provides storage for programs and processing powerto implement test regimens in a logical order relating to completion ofthe inspection. Full integration of an OBC to an individual vehicleinspection procedure to promote efficiency and completeness, and toavoid possible damage to the vehicle, aids organization of the taskscalled for by the inspection.

The substantially automated inspection system of the present inventionworks with a vehicle having an engine and with various vehicle systems,characterized by measurable operating variables. The system includes anelectrical system controller, a data communications bus connected at onenode to the electrical system controller, a plurality of sensorsconnected to the data communications bus for transmitting data relatingto the operating variables to the electrical system controller, an userinput/output interface, an on board computer connected to the userinput/output interface and to the data communications bus, the on boardcomputer including memory, and a vehicle inspection regimen stored inthe memory and executable on the on board computer. The program providesmeans for checking fluid levels against one or more limits for variousvehicle systems before engine start, means for prompting an operator tostart the engine if the operating fluid levels meet applicable limits,and means for completing the vehicle inspection regimen after an enginestart.

Additional effects, features and advantages will be apparent in thewritten description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself however, as well as apreferred mode of use, further objects and advantages thereof, will bestbe understood by reference to the following detailed description of anillustrative embodiment when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a partial cutaway view in perspective of a truck incorporatingthe invention;

FIG. 2 is a block diagram of a computer control, network and sensorsystem used to implement the inspection protocols; and

FIG. 3 is a flow chart illustrating the order of execution of theinspection program.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view of a truck 11 and of an electrical controlsystem 10 installed on the vehicle. Electrical control system 10comprises a twisted pair (either shielded or unshielded) cable operatingas a serial data bus 18. One node of bus 18 is an electrical systemcontroller (ESC) 30, which is the central component of a vehicleelectronic control system. ESC 30 manages a number of vocationalcontrollers connected to bus 18 as nodes and positioned on truck 11.Collectively, bus 18 and the various nodes attached thereto form acontroller area network (CAN). Truck 11 includes the conventional majorsystems of a vehicle, including an engine, a starter system for theengine, brakes, a transmission and running lights.

Active vehicle components are typically controlled by one of a group ofautonomous, vocational controllers, which include a gauge cluster 14, anengine controller 20, a transmission controller 16, an auxiliaryinstrument and switch bank 12, and an antilock brake system (ABS)controller 22, all of which are nodes on serial data bus 18 allowing twoway communication with ESC 30. Autonomous controllers include local dataprocessing and programming and are typically supplied by themanufacturer of the controlled component. Bus 18 is a twisted pair cableconstructed in accordance with SAE standard J1939. Although theautonomous controllers handle many functions locally and can functionindependently of ESC 30, they report data to ESC 30 and can receiveoperational requests from ESC 30.

An on board computer (OBC) 40 is also provided on truck cab 11. OBC 40is based on a conventional personal or portable computer architectureand communicates with ESC 30, either over bus 18, or directly over aprivate bus. OBC 40 executes an inspection protocol leading togeneration of required inspection and maintenance reports.

FIG. 2 is a block diagram of the electrical control system 10. ESC 30can collect data from a variety of sources, both over serial data bus18, or from sensors and devices directly connected to the ESC. Onesensor illustrated as directly connected to a port on the ESC 30 is arear axle fluid level sensor 46. Electrical system controller 30 alsodirectly actuates lights 52 and can determine whether lights are workingfrom the amount of current drawn. ESC 30 and OBC 40 may communicate overthe serial data bus 18 or over a dedicated private bus 19. OBC 40includes conventional memory 43 (both volatile and non-volatile) andprogram execution capacities (CPU 41).

A serial data bus 18 conforming to the SAE J1939 standard provides fordata communication between ESC 30 and an engine controller 20, atransmission controller 16, ABS controller 22, instrument and switchbank 12, a gauge cluster 14 and one or more sensor interface modules.These controllers and modules are in turn connected to one or moresensors which they collect data from and to which they may return datawhich relate to the sensors to ESC 30. The specific connections betweensensors and nodes of the system is exemplary, and other arrangementsthan the one illustrated are possible.

Engine controller 20 is connected to an engine coolant level sensor 25,an engine coolant temperature sensor 26, an engine oil level sensor 27,an engine oil temperature sensor 28 and an engine oil pressure sensor29. Engine coolant level sensor 25 is typically either a pressure orcapacitive type sensor, and is located at a position in the coolantsystem allowing level sensing while the vehicle is stationary. Thesensor has either a binary output (1=level acceptable, 0=add coolant),or an analog output indicating percentage full (50% to 120% full). Thesensor has a maximum sample rate of 1 measurement per second.Measurements can be broadcast on bus 18 formatted in accordance withJ1939 PGN65263. The engine coolant temperature sensor 26 is preferablylocated at a position in the engine coolant flow system allowing takingtemperature readings during engine operation. This sensor has a range of−40° C. to 125° C., with a maximum sampling rate of 1 reading persecond. Measurements can be taken after the engine has been running aminimum length of time. These measurements can be broadcast on bus 18formatted in accordance with J1939 PGN 65262.

Engine oil level sensor 27 is either a capacitive or pressure typesensor, and is located at a position in the engine oil flow systemallowing engine oil level sensing while the vehicle is level. Sensor 27has either a binary output (1=level acceptable, 0=add oil), or an analogoutput indicating percentage full. If the output is analog, analog todigital conversion can be provided. Sensor 27 provides sampling at 2 Hz.Messages containing measurement data are transmitted over bus 18 inaccordance with J1939 PGN 65263. Engine oil temperature sensor 28 islocated in the oil flow system allowing measurements when the engine isrunning. Sensor 28 has a temperature operating range of −40° C. to 125°C., with a 1 Hz operating cycle. The message data format is J1939 PGN65262. Engine oil pressure sensor 29 is located in the oil flow systemto sample pressure during engine operation. Sensor 29 has an operatingrange of 0 psi to 200 psi with a sampling rate of 2 Hz. The messageformat is J1939 PGN 65263.

Transmission controller 16 is connected to a transmission fluid levelsensor 32 and, usually, to a transmission fluid temperature sensor 33.Transmission fluid level sensor 32 is typically a capacitive or pressuretype sensor, and is located in the transmission fluid flow system toobtain fluid level measurements when the vehicle is level andstationary. Sensor 32 may have an analog output (50% to 120% of full) ora logical binary output (1=level acceptable, 0=add fluid). The samplingrate is 1 Hz. The signal is routed to the transmission controller 16 andbroadcast on bus 18 as a J1939 PGN 65272 signal. Transmission fluidsensor 33, while frequently connected to transmission controller 16, issometimes directly connected to ESC 30. The sensor has an operatingrange of 40° C. to 125° C. and a 1 Hz sampling rate. Measurements, ifrouted through transmission controller 16, are formatted for data bus 18as a J1939 PGN 65272.

The anti-lock brake system (ABS) controller 22 controls the brake systemand is typically connected to brake system pressure sensors 34 and brakeactuation sensor 38, analysis of measurements from which allowdetermination of brake system functionality. OBC 40 will directexecution of an procedure to determine if the components of the vehiclebrake system are functioning correctly. Brake system pressures arebroadcast on bus 18 as a J1939 PGN 65274 signal. The OBC 40 can issueinstructions to ESC 30, some for further transmission to the appropriatecontroller, to set and hold engine speed, to depress or pump the brakes(via brake system actuation 37) and for setting and releasing theparking brake 51. Alternatively, OBC 40 may prompt the driver/operatorto carry out these tasks by the user I/O interface 36.

A power steering fluid level sensor 44 is located in a power steeringfluid reservoir (not shown) and may be connected either to ESC 30, toengine controller 20, or, as illustrated here, to a sensor interfacemodule (SIM) 45, which communicates with ESC 30 over bus 18. The sensorhas either a binary output (1=level acceptable, 0=add fluid), or ananalog output indicating percentage full (from 50% to 120%). The sensorsampling rate is 1 Hz. Transmission of the data is broadcast on bus 18as a J1939 PGN 65272 message.

Fuel level sensors 48 are located in the vehicle's fuel tanks (notshown) and may be connected either to ESC 30, or, as illustrated here,to a SIM 53, which communicates with ESC 30 over bus 18. The sensor hasan analog output indicating percentage full (from 0% to 100%). Thesensor sampling rate is 1 Hz. SIM 53 provides analog to digitalconversion of the sensor output and broadcast of a data message on bus18 as a J1939 PGN 65276 message.

A windshield washer fluid level sensor 48 is located in a windshieldwasher fluid reservoir (not shown) and is typically connected to a SIM49, which communicates with ESC 30 over bus 18. The sensor has a binaryoutput (1=level acceptable, 0=add fluid). The sensor sampling rate is 1Hz. Transmission of the data is broadcast on bus 18 as a J1939 PGN 65276message.

Electrical system controller (ESC) 30 is represented as communicatingdirectly with a number of devices. Such connections may be provided viaports which may be configured as power supply ports or serial dataports. Vehicle lights 52 are powered directly from ports on ESC 30. Theoperational integrity of vehicle lights 52 may be determined by currentdrawn. Other devices or sensors may similarly be directly connected toESC 30, or they may be connected to bus 18 by a sensor or deviceinterface module allowing data to be broadcast to ESC 30, or devices andsensors may be handled by one of the other autonomous controllers, suchas engine controller 20. Rear axle oil level sensor 46 is connectedeither directly to ESC 30, or by a sensor interface module to bus 18.Sensor 46 may have either an analog output (50% to 120% of full),converted to digital data, or a binary output (1=level acceptable, 0=addoil). The maximum sampling rate is 1 Hz. The J1939 specification doesnot assign a message format for rear axle differential oil level,requiring a proprietary message format if transmission of data ishandled by a SIM.

ESC 30 is connected to a battery condition sensor 24. Battery conditionsensor 24 preferably represents a system comprising ammeters coupled tobattery leads, battery voltage sensing and temperature sensors. Thedetermination of battery capacity and charge entails execution of analgorithm and reference to battery performance and history tables. Thecomplexity of the system may vary from application to application andthe system may, in some circumstances, be different. This algorithm maybe executed by OBC 30, which also provides for storage of a conditionevaluation algorithm and the needed tables on memory 43. OBC provides aCPU 41 to execute the algorithm. Data relating to battery 23 is passedthrough ESC 30 from battery condition sensor 24.

ESC 30 is also connected to a tire pressure sensor 42. Tire pressuresensing may be provided for in a number of ways, including inferentialpressure measurement based on relative tire rotational velocities (inwhich case measurements may be handled by the ABS controller 22), or bydirect methods, such as battery powered sensors mounted in the tires, inwhich case the pressure measurements may be directly communicated by aconnection between the sensors 42 and ESC 30. A gauge cluster 14 and aninstrument and switch bank 12 communicate with ESC 30 over data bus 18.Additional components may be attached to bus 18 and accommodated by theinspection routine if deemed important, such a pump controller on a fueltanker.

Driver inputs and prompts are handled by user I/O interface 36, whichmay be implemented in a touch screen display, conventional displays, andkeyboards or pads. I/O interface 36 is under the direct control of OBC40, accepts driver indication of task completions, including in cab andwalk around inspection items, and further directs aspects of the brakeinspection routine which cannot be economically automated. Driveracknowledgment of critical errors requiring immediate attention isprovided. Prompts or buttons in interface 36 allow for this. OBC 40 canprovide for storage of reports in memory 43, which includes volatile andnonvolatile sections. Alternatively, the interface 36 may include aprinter allowing hard copies of the reports to be printed. As describedabove, some aspects of the inspection procedure can require driveractions, such as pumping or depressing the brakes, which are prompted onI/O interface 36. For walk around portions of the inspection a wirelesshandheld unit 136 may by be used by the driver to receive prompts fromOBC 40 via a wireless communication card 135.

FIG. 3 is a high level flow chart illustrating one possible procedureexecuted on OBC 30 to implement a preferred embodiment of the invention.The exemplary procedure begins with movement of the vehicle key to theon position from OFF (step 54). At step 56 it is determined if thepre-trip inspection mode has been triggered. These can occur at: (1) therequest of the driver; (2) each time the key is moved from off to on;(3) each key on instance after a minimum time interval since the lastkey on instance; (4) each key on instance when the engine coolanttemperature is below a minimum threshold; (5) each occasion of a changeof driver; (6) a specific time of day; or (7) a minimum time intervalsince the last inspection. Particular triggering condition(s) areselected at the time when an OBC 30 is configured for a particularvehicle. The selections remain in effect until changed by theuser/operator. Interrogation of the inspection triggering conditions isindicated by step 55. If none of the conditions is matched the routineis exited.

The routine has a pre-engine start segment (steps through step 76) and apost engine start segment (steps 78 to 97). If at step 56 an inspectionis indicated, step 58 is executed to determine if the last inspectionreport, stored in memory 43, has been signed off. By “signed off” isusually taken as indication by a driver, possibly using a password orcode, that an inspection was performed. Step 58 can also be used toforce branching to step 60, for example in the case that it is simplydesired to review the report. If not, the branch to step 60 is taken andthe driver is prompted to review the last inspection report and to makenotes and sign off on the report at step 62. Following verification ofsigning off on the previous report (the YES branch from step 58 orfollowing step 62), inquiry is made by the I/O interface 36 to thedriver as whether to begin the inspection (step 64). In not, for examplein the situation where review of a prior report had been required, theprogram may be exited by step 65.

Following the YES branch from step 64 an inspection of the vehicle isbegun. At step 66 all fluid level sensors are interrogated. Next, atstep 68, the fluid level measurements are compared to minima criteriafor acceptability. For each fluid level not meeting recommended levelsstep 69 is executed along the NO branch from step 68 to set a fluidlevel error flag. Upon analysis of all fluid levels processing isrepresented as progressing to a step 70 dealing with a default errorflag for automatic transmission fluid level. Low transmission fluidlevel can result in catastrophic transmission damage and an engine startis not permitted unless transmission fluid level is confirmed to beabove a minimum. If transmission fluid level is below the flag minimumanother fluid level error flag algorithm is run (step 74) followed bydetermination as to whether the fluid level, even though belowrecommended minimums, is sufficient to allow a safe start (step 76).These steps occur only if the message relating to transmission fluidlevel is expressed in terms of percentage of full. If it is not, theroutine is exited (step 77), otherwise, or following the YES branch fromstep 72, processing continues to step 78 and a prompt to the driver tostart the engine.

Once the engine has been started battery condition may be updated. Ifbattery condition is determined as unacceptable at step 80 a flagindicating the need for maintenance is set. Next the several pressureand temperature readings are compared to norms, and if any are out ofnorm, processing is temporarily interrupted (step 82) to set theappropriate flag (step 83). Then step 84 is executed to compare tirepressure measurements against minimum required levels. If a tire hasinadequate pressure a flag is set (step 85). Following step 84 thedriver is prompted to turn on the vehicle's lights (step 86). At step 88the current drawn by the lights is compared with the minimum figureindicating that the lights are all working. If current draw is low aflag is set at step 89. Next the driver is prompted to perform in caband walk around checks. A handheld display device may be used at thispoint. Step 92 represents execution of brake system checks, which may beautomated or manual. Brake system is operation is compared withacceptable operating variables at step 94. If a variable is out of norma brake system error flag is set using a sub process (represented bystep 95). Finally, at step 96 a new inspection report is generated andthe program is exited (step 97).

The present invention automates many applicable portions of a pre-tripinspection and provides immediate return information to the driver inthe form of a electronic inspection report. This in turn saves both timeand helps insure completeness of the reports.

While the invention is shown in only one of its forms, it is not thuslimited but is susceptible to various changes and modifications withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A vehicle having an engine and various vehiclesystems having operating fluids and characterized by operating fluidlevels, the vehicle comprising: an electronic system controller; a datacommunications bus connected at one node to the electronic systemcontroller; a plurality of sensors connected to the data communicationsbus for transmitting data to the electronic system controller; an userinput/output interface; an on board computer connected to the userinput/output interface and to the data communications bus, the on boardcomputer including memory; and a vehicle inspection regimen stored inthe memory and executable on the on board computer, providing, means forevaluating a plurality of preset inspection triggering conditions, thepreset inspection triggering conditions including one or more of thefollowing; request by the driver, movement of an ignition key from anoff to an on position, movement of the ignition key from an off to an onposition after a minimum time interval from a previous occurrence ofmovement of the ignition key from the off to the on position, movementof the ignition key from off to on when an engine coolant temperaturereading is below a minimum, occasion of a change of driver of thevehicle, a specific time day, and a minimum time interval since theprevious inspection, means for checking fluid levels against one or morelimits for various vehicle systems before engine start, means forprompting an operator through the user input/output interface to startthe engine if the operating fluid levels meet applicable limits; andmeans for completing the vehicle inspection regimen after an enginestart.